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Developing highly porous and conductive carbon electrodes are crucial for high-performance electrochemical double-layer capacitors. Herein, we provide a supercapacitor electrode material consisting of N-doped porous carbon tightly anchored on carbon nanotubes. This nanocomposite with high specific surface area of 659.5 m 2 g −1 is fabricated by pyrolyzing the ZIF-8/polypyrrole nanotubes. When the nanocompiste is used as supercapacitor electrodes, it deliveres high specific capacitance of 248 F g −1 and 97.3% of capacitance retention after 3000 cycles. The superior capacitive performance is attributed to the conductive network for electron transport constributed by CNTs and the abundant reservoir for the charge storage derived from ZIF-derived porous carbon. Benefiting from the unique structural features and high N doping, the PC-CNTs obtained by our route could be a promising candidate of electrode mateials for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

• A three-dimensional Ni,Co-embedded CNT-coated N-doped hollow porous carbon (Ni/Co-CNT/NHPC) cathode has been designed and prepared for lithium-sulfur battery. • The Ni/Co-CNT/NHPC-S cathode possesses a high specific capacity of 1352 mA h g-1 and an excellent cycle stability at 1 C with low capacity decay of 0.094% per cycle over 500 cycles. • The mechanism of suppressing the shuttle effect on the cathode materials is discussed by analyzing adsorption experiments and density functional theory（DFT）calculation. Lithium-sulfur (Li-S) batteries have attracted great attentions due to their high specific capacity. However, the poor cycle stability caused by polysulfide shuttles, volume expansion and formation of lithium dendrites limit their practical applications. In the present work, to tackle the poor stability and unstable rate capability, a MOF-doping strategy is developed to construct a hollow porous carbon framework，which consists of Ni, Co particles and CNT on a N-doped shell surface (Ni/Co-CNT/NHPC). This hollow framework increases the load of S, slows down the volume changes, and can physically entrap soluble polysulfide. It is found that the CNT-coated network structure is beneficial for optimizing the conductivity and wettability of the material, which accelerates the reaction kinetics. Moreover, synergistic effect of abundant defects and Ni, Co nanoparticles strengthens the chemisorption of polysulfides, which suppresses the shuttle effect. As a consequence, the Ni/Co-CNT/NHPC-S cathode harvests a high specific capacity (1352 mA h g-1), and shows an excellent cycling stability at 1 C with low capacity decay of 0.094% over 500 cycles. [ABSTRACT FROM AUTHOR]

Currently, with the rise of the photovoltaic industry, how to effectively treat waste silicon powder from an environmentally friendly and economic point of view becomes significant. We reported a simple method to prepare the "core-shell" structure of silicon/carbon nanotubes/carbon (Si/CNTs/C) composite by ball-milling using waste silicon powder. Specifically, The synergistic effect of CNTs and amorphous carbon matrix is beneficial to improving the transmission rate of Li-ions and electrons, and facilitating the reaction kinetics of Li-ions in the process of lithiation/de-lithiation. Meanwhile, the carbon coating layer reduces the direct contact between silicon and the electrolyte, which greatly alleviates the volume expansion of silicon in cycling. With these merits, Si/CNTs/C anode shows high rate performance and outstanding cycling stability up to 300 cycles at 0.2C. Furthermore, full cells assembled with pre-lithiated Si/CNTs/C anodes and commercial NCM811 cathodes deliver considerable initial coulombic efficiency (84.4%) and high energy density (502 Wh kg−1). Si/CNTs/C composites prepared by ball-milling show excellent long-cycle stability and rate performance. [Display omitted] • Industrial waste silicon is used to prepare silicon-based anodes. • Two-step ball milling method to prepare Si/CNTs/C composite. • A solution-based chemical prelithiation method is proposed. • Si/CNTs/C anode exhibits excellent long-cycle stability and good rate performance. • A full cell shows an improved ICE (84.4%) and a higher energy density (502 Wh kg−1). [ABSTRACT FROM AUTHOR]

N-doped porous carbon nanosheets were prepared from glucose with g-C 3 N 4 derived from dicyandiamide as a self-sacrificed template, which have a high nitrogen content of 12.01 at.% and a specific surface area of 492.7 m 2  g −1 . The unique structure allows for exhibiting high specific capacitance of 250.64 F g −1 and excellent rate capability. [ABSTRACT FROM AUTHOR]

The porous carbon microtubes/flakes composites are prepared via a facile hydrothermal treatment with bamboo chopsticks as a carbon precursor and KOH as an activating agent. The as-prepared samples possess the large specific surface area up to 2337 m 2 g −1 . They exhibit the high specific capacitance of 212 F g −1 at a current density of 0.1 A g −1 , and the capacitance retention remains 96% after 1000 cycles in 6 M KOH. The results indicate that the natural resource of bamboo chopsticks could be an essential raw material for the energy storage devices. [ABSTRACT FROM AUTHOR]